Windows 8 Consumer Preview – It's Windows reimagined and reinvented.
Visual Studio 11 Express Beta for Windows 8 – Tool to build Metro style apps for Windows 8.
200 Win8 Sample AppPack - This package contains over 200 samples from Microsoft.
Metro Style Design Assets - These .psd assets include templates, common controls, and common components.
Bing Maps for Windows8 XAML+C# SDK - Binaries & programming ref for the Bing Maps Win8 Control
Live SDK -The Live SDK provides a set of controls and APIs that enable applications to integrate Single Sign On Multilingual App Toolkit for Visual Studio 11 Beta - Localize your Metro style app with translation support
Microsoft Advertising SDK for Windows 8 – choose whichever ad platform you prefer in your app.
Get started with Metro style Apps - get started building exciting apps that are alive with activity.
Get started with Visual Studio 11 Beta – Phone development extensions for Visual Studio 2010
Get started with Blend for Visual Studio 11 Beta – Cloud services running in Windows Azure
Design assets for Metro style apps – Design principles, UX design patterns, detailed UX guidelines
Windows Dev Center Home – Links to Metro style app, Desktop app, Hardware, and IE development.
Learn to build Metro style apps – This guide walks you through the essentials of writing your first app.
Developer forums - Developer forums for Metro style apps covering designing, developing, and selling apps.
Selling apps in the Windows Store - Windows Store markets, developer agreements, and checklists to prepare.
Building Windows 8 blog (B8) – An inside look at how, what, and why different features of Win8 are being built.
Windows 8 app developer blog (D8) – Explores best practices for coding and designing Metro style apps
http://www.buildwindows.com/ - Windows 8 Keynote and session videos